The hunt for water plume activity on Jupiter moon Europa

Jupiter’s moon Europa might harbor life in its vast water ocean below the thick ice crust. This deep subsurface habitat could potentially be investigated at locations of active outgassing, giving the question whether Europa is geologically active a crucial importance. However, evidence for present-day activity remained elusive for decades. Now several recent studies derived the existence of outgassing water plumes on various locations. These studies used a variety of methods from remote-sensing telescope observations to in-situ spacecraft magnetic field and plasma wave measurements. Just two weeks ago a study was published with observations by the Keck telescope in Hawaii, which provided a first tentative but direct detection of water vapor around Europa. Yet, the final proof for the existence of active water plumes is still missing. I will review the different studies claiming evidence and explain why we still do not understand Europa’s plume activity.